Mario Kart Tour (iOS)

Rocket Start
During the starting line countdown, tap and hold the screen when the "2" appears and release at "GO!" to get the best possible Rocket Start.
My 'Shroom
You can get a speed boost from driving into a Mushroom that another racer is towing. The other driver apparently does not lose the Mushroom, so it's possible to get multiple boosts from it. Note: This does not work with Mega Mushrooms.
Disappearing ink
When your screen is gooped up with Blooper ink, you can quickly clean it off by using a Mushroom, driving over a Dash Panel, or performing a Mini-Turbo or Jump Boost. You can also wipe off the ink blot with your finger if you don't want to wait for it to go away on its own.